From: Alan Friedman <alan@greatarrow.com>

Date: February 11, 2006 2:00:15 PM MST

To: Astro_IIDC@yahoogroups.com

Subject: Re: [Astro_IIDC] Re: Saturn at Opposition


Hi Duane -


Thanks! Did he post the link to APOD? It has gotten quite a bit of play recently on NASA science news and Spaceweather too. It's a nice image but I think the lunar/Italian alp connection was a good hook. 


I was excited to have the Plato/Alpes image chosen for APOD - they don't use much earthbound lunar/planetary stuff.


This image was made from 20 streams of data captured on August 25th (hasn't been much opportunity to see the moon here over the last few months) - I finished processing the mosaic during the last couple of weeks. I posted a link to the image here in a previous post, I think.


What is the Macastronomer group - I don't know that one?


best,

Alan



On Feb 11, 2006, at 3:48 PM, Duane wrote:


Alan, your lunar shots on nasa's site are spectacular. David Illig just posted links to it in 

macastronomer group.


Is that an older shot or a recent one?


Duane


--- In Astro_IIDC@yahoogroups.com, Alan Friedman <alan@...> wrote:

>

> Hi Duane -

> 

> I believe Milton posted a link to Wes' web index in an earlier post. He 

> is an active participant in the Astromart Planetary Imaging forum 

> (which is a great forum for this topic, BTW). His lunar work with an 

> 18" Starmaster is the best I've seen from this planet.

> 

> I thought I would copy a post I made earlier today on the Astro-Physics 

> forum. Seeing is huge, no doubt - but be sure to have a look at 

> Damian's mars images from the UK in average - good seeing. There is 

> hope short of lugging all your stuff down south!

> 

> I hope to have a website live by the end of this month - thanks for 

> asking.

> 

> cheers-

> Alan

> 

> ps - the whiner I refer to in my post below is me, not you!  8^)

> 

> -----------------------------

> 

> Hi Milt -

> 

> I think your comments are a good summary. In planetary imaging, seeing 

> is still a

> critical factor - but it factors differently than in visual because you

> can pick the

> image apart into 33ms bits, choose the good ones and eliminate the bad 

> ones. In

> this way, the seeing is not a monolithic experience. In virtually every 

> stream there

> are images typical of 6/10 seeing and 3/10 seeing - the question is how 

> many are

> of the 6/10 variety in a period of time before features move and can no 

> longer be

> averaged to reduce noise. The Pickering scale as we use it for visual 

> observing

> does not really work well to describe limits for planetary imaging (I 

> wonder how

> many imagers begin and end their sessions with a star test - poor, 

> fair, good, very

> good might be just as useful).

> 

> While we often talk (and whine) about the seeing conditions it is 

> important to

> remember that very good imaging results can be obtained in fair-good 

> seeing (5

> -6/10). You need enough aperture for adequate light to record with a 

> long focal

> length. Assuming good processing skills, in conditions where 600 frames 

> at 6/10

> quality can be gleaned and averaged, the postion of the Encke division 

> will be

> recorded over a good section of the ansae of saturn's rings.

> 

> These conditions can drift in and out many times over a 30 minute 

> observing

> session and can be found during some part of the night in almost any 

> location. A

> big part of the challenge is getting out frequently enough to catch 

> them. Damian's

> images are truly spectacular - also remember that he has been out to

> image mars

> more than 100 times during this apparition.

> 

> steady skies!

> Alan

> 

> 

> 

>   ---------- Original Message ----------------------------------

> From: "wilcoxmilton" <wilcoxmilton@...>

> > I guess the difference must be that in imaging you get to stack so

> > many frames (hand picked?) that it effectively neutralizes the effects

> > of mediocre seeing?  At the eyepiece, I find it extremely difficult to

> > mentally register the detail available in brief moments of clarity (I

> > know I am not in the skill class of many of the visual planetary

> > observers here).

>







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